Heat spreader with flexible tolerance mechanism

ABSTRACT

A semiconductor device packaging system includes a substrate, a heat spreader, a stiffener attached to the substrate, and at least one die electrically coupled to the substrate and thermally coupled to the heat spreader. The semiconductor device packaging system further includes at least one stud coupled to one of the stiffener and the heat spreader and at least one orifice formed through one of the stiffener and the heat spreader. In addition, the at least one orifice is aligned with the at least one stud.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a non-provisional of, and claims priority to,U.S. Provisional Patent Application Ser. No. 61/733,138, filed Dec. 4,2012, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Embodiments of the invention relate generally to a semiconductor devicepackaging assembly and a method of making the same.

A common practice of packaging semiconductor dies involves mounting asingle semiconductor die on a package substrate composed of laminate ororganic materials, such as epoxy resins. More recently, experts in thefield have introduced multi-die systems. In this practice, at least oneor more semiconductor dies are positioned on a single package substrate.In some of these systems, one or more of the semiconductor dies may behigh power devices, such as microprocessors, and others may be lowerpower devices, such as memory and voltage regulator devices.

As a result of having a hybrid package of high power and low powersemiconductor dies, the thermal management apparatus of the package mayrequire a thermal management mechanism such as a heat spreader inthermal contact with the semiconductor dies by way of thermal interfacematerial layers. However, the varying thicknesses and tolerances of eachcomponent affect the thermal connection of the multi-die system. Inaddition, another level of tolerances can be introduced due to warpingduring the assembly process of these components. In turn, these varyingdimensions can lead to a low yield from the completed package andmanufacturing challenges.

The current state of the art attempts to protect a package, which has anexposed die during the assembly, from warping by introducing a metalring to act as a stiffener 10, as shown in FIG. 1. FIG. 1 illustrates asemiconductor device package assembly 12 including stiffener 10 attachedto a substrate 14 via an adhesive 16. In addition, a die 18 is attachedto substrate 14. However, during the assembly process, package assembly12 can face another level of warping due to the high temperatureconditions of processes such as the reflow process. The warping is worsewhen the assembly introduces multi-die configurations.

FIG. 2 illustrates a semiconductor device package assembly 20 having aheat spreader 22, which is in contact with die 18 through a thermalinterface material 24. Heat spreader 22 is further secured to stiffener10 via adhesive 16. Due to warping during the assembly process and thediffering thicknesses of the components, the thermal connection betweenheat spreader 22 and die 18 may not be appropriately established onceheat spreader 22 is secured to stiffener 10, resulting in packageassembly 20 having a low yield.

FIG. 3 depicts a semiconductor device package assembly 26 havingmultiple dies. In these configurations, one or more of the dies 18 maybe high power devices, such as microprocessors, and others may be lowpower devices, such as memory and voltage regulator devices. As aresult, the thermal management of assemblies having a hybrid of highpower and low power dies 18 may require a thermal management mechanismsuch as heat spreader 22. Heat spreader 22 is in thermal contact withthe semiconductor dies 18 by way of thermal interface material layers24. Thermal interface material layers 24 can be solder-based, which hascertain advantages for high powered devices due to the ability of solderto withstand higher temperatures and the greater thermal conductivitythereof. Thermal interface materials layers 24 may also be an organicmaterial. However, under certain circumstances, the usage of heatspreader 22 with either organic or solder paste thermal interfacematerial layers 24 can lead to additional warping.

As a result, there are many different scenarios during the assemblyprocess of a semiconductor device package assembly that can lead towarping. Warping, in addition to the varying dimensions of multiplecomponents, can lead to a low yield for the completed package.Therefore, it would be desirable to provide a flexible tolerance heatspreader that is able to be secured in a variety of locations along asupport stud, as opposed to a single location atop a stiffener. Thiswould allow the heat spreader to adapt its location in order toestablish maximum thermal contact between the heat spreader and thecomponents of the package assembly, resulting in being able to maintainthe yield of a package even with the addition of multiple dies.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one aspect of the invention, a semiconductor devicepackaging system includes a substrate, a heat spreader, a stiffenerattached to the substrate, and at least one die electrically coupled tothe substrate and thermally coupled to the heat spreader. Thesemiconductor device packaging system further includes at least one studcoupled to one of the stiffener and the heat spreader and at least oneorifice formed through one of the stiffener and the heat spreader. Inaddition, the at least one orifice is aligned with the at least onestud.

In accordance with another aspect of the invention, a method ofassembling a semiconductor device package includes electrically couplingat least one die with a substrate, coupling a stiffener to thesubstrate, and coupling at least one stud to one of the stiffener and aheat spreader. The method further includes forming at least one orificethrough one of the stiffener and the heat spreader, aligning the atleast one stud with the at least one orifice to align the heat spreader,the stiffener, and the at least one die, and thermally coupling the heatspreader with the at least one die.

In accordance with yet another aspect of the invention, a flexibletolerance heat spreader for use with a semiconductor device packageincludes at least one support path formed through the flexible toleranceheat spreader, wherein the at least one support path interacts with atleast one stud coupled to a stiffener of the semiconductor devicepackage. In addition, the flexible tolerance heat spreader is variablypositioned along a direction of the interaction of the at least onesupport path and the at least one stud to establish guidance of theflexible tolerance heat spreader to provide thermal contact with atleast one die of the substrate.

These and other advantages and features will be more readily understoodfrom the following detailed description of preferred embodiments of theinvention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments presently contemplated for carryingout the invention.

In the drawings:

FIG. 1 is a front perspective view of a prior art semiconductor devicepackage assembly.

FIG. 2 is a front perspective view of a prior art semiconductor devicepackage assembly including a heat spreader.

FIG. 3 is a front perspective view of a prior art semiconductor devicepackage assembly including a heat spreader and multiple dies.

FIG. 4 is a front perspective view of a semiconductor device packageassembly, according to an embodiment of the invention.

FIG. 5 is a front perspective view of a semiconductor device packageassembly using components with greater thicknesses, according to anembodiment of the invention.

FIG. 6 is a front perspective view of a semiconductor device packageassembly using components with smaller thicknesses, according to anembodiment of the invention.

FIGS. 7.1-7.2 are top perspective views of semiconductor device packageassemblies illustrating different locations of support studs in thestiffener, according to embodiments of the invention.

FIGS. 8.1-8.4 are front perspective views of semiconductor devicepackage assemblies illustrating different configurations of one or moredies and an interposer, according to embodiments of the invention.

FIG. 9 is an enlarged view of the support stud of FIG. 4 including aplated layer, according to an embodiment of the invention.

DETAILED DESCRIPTION

First referring to FIG. 4, a front perspective view of a semiconductordevice packaging assembly 28 according an embodiment of the invention isillustrated. In this embodiment, one or more dies 30 are attached to asubstrate 32. It is contemplated that dies 30 can be any combination ofhigh power devices and low power devices. Further, dies 30 may havevarying thicknesses. Although FIG. 4 depicts the use of three (3) dies30, it is contemplated that the semiconductor device package can includemore or less than three (3) dies 30 attached to substrate 32. Inaddition, a stiffener 34 is attached to substrate 32 via an adhesive 36.Stiffener 34 may be a metal ring disposed along the outer perimeter ofsubstrate 32. In this embodiment, two (2) support studs 38 are attachedto stiffener 34. While FIG. 4 illustrates the use of two (2) supportstuds 38, it is contemplated that the semiconductor device package canuse more or less than two (2) support studs 38.

The semiconductor device packaging assembly 28 also includes a heatspreader 40. Heat spreader 40 includes orifices or support paths 42formed through heat spreader 40 and designed to align with support studs38. Once again, while FIG. 4 illustrates the use of two (2) supportpaths 42 to coincide with the two (2) support studs 38, it iscontemplated that heat spreader 40 may have more or less than two (2)support paths 42 formed therein to coincide with the semiconductordevice package having more or less than two (2) support studs 38. Athermal interface material 44 is added to the top portion of each die 30in order to assist with the thermal connectivity of dies 30 and heatspreader 40 in the completed semiconductor device package.

The interaction between support studs 38 and support paths 42 formed inheat spreader 40 allows for the positioning of heat spreader 40 to beadjusted in the direction of support studs 38. The adjustablepositioning of heat spreader 40 and the deforming of thermal interfacematerial 44 allows for thermal contact between heat spreader 40 and eachdie 30 to be established, even if dies 30 have different thicknesses. Asa result, the yield of the package is not sacrificed by the multi-diearrangement.

As shown in FIGS. 5 and 6, a semiconductor device package assembly 46can have varying thicknesses depending on the combination of componentswithin the assembly. FIG. 5 illustrates the use of dies 30 and thermalinterface materials 44 having a large combined thickness. In thisinstance, stiffener 34 and heat spreader 40 are not in direct contactwith one another, and an air gap 48 is formed between stiffener 34 andheat spreader 40. The disposition of support studs 38 within supportpaths 42 keep heat spreader 40 properly aligned while the verticalplacement is adjusted to properly fit dies 30 and thermal interfacematerials 44. The vertical placement of heat spreader 40 reaches itsmaximum height when support studs 38 are no longer within support paths42 to keep heat spreader 40 in proper alignment.

FIG. 6 depicts the use of dies 30 and thermal interface materials 44having a small combined thickness. In this instance, stiffener 34 andheat spreader 40 are in contact with each other. The distance betweenheat spreader 40 and substrate 32 is at its minimum value when heatspreader 40 and stiffener 34 come in to direct contact with each other,and heat spreader 40 is no longer able to move closer to substrate 32.

The vertical placement of heat spreader 40 is able to be adjustedbetween the maximum height depicted in FIG. 5 and the minimum heightshown in FIG. 6. This flexibility allows heat spreader 40 to accommodatecomponents with varying thickness and tolerances and establish thermalcontact with each die 30 used in the semiconductor device packagingassembly 46. As a result, the yield is not sacrificed, even with theaddition of multiple components.

FIGS. 7.1-7.2 illustrate different possible configurations of supportstuds 38 and support paths 42. As shown in FIG. 7.1, one embodiment ofthe invention has a semiconductor device package assembly 50 containingtwo (2) support studs 38 coupled to opposing walls of stiffener 34. Inthis embodiment, heat spreader 40 (not shown) contains two (2) supportpaths 42 (not shown), mirroring the location of support studs 38, toalign heat spreader 40 (not shown) with stiffener 34 and dies 30. FIG.7.1 shows support studs 38 located on opposite walls of stiffener 34,along a center axis of the semiconductor device package assembly 50.However, it is contemplated that each support stud 38 may be located atany point along the walls of stiffener 34. Further, package assembly 50may have more or less than two (2) support studs 38 coupled to stiffener34 at any location along the walls of stiffener 34. Therefore, it isalso contemplated that heat spreader 40 (not shown) may contain more orless than two (2) support paths 42 (not shown) to coincide with thenumber of support studs 38.

FIG. 7.2 illustrates another embodiment of the invention has, wherein asemiconductor device package assembly 52 includes four (4) support studs38, one support stud 38 in each corner of stiffener 34. In thisembodiment, heat spreader 40 (not shown) contains four (4) support paths42 (not shown), mirroring the location of support studs 38, to properlyalign heat spreader 40 (not shown) with stiffener 34 and dies 30. WhileFIG. 7.2 shows the use of four (4) support studs 38, it is contemplatedthat package assembly 52 may contain more or less than four (4) supportstuds 38. In addition, it is contemplated that package assembly 52 mayalso contain more or less than four (4) support paths 42 (not shown), tocoincide with the number of support studs 38.

While FIG. 7.1 illustrates support studs 38 located along the walls ofstiffener 34 and FIG. 7.2 depicts support studs 38 located in thecorners of stiffener 34, it is contemplated that less than all supportstuds 38 may be located on the walls of stiffener 34 and the remainingsupport studs 38 may be located in the corners of stiffener 34.

Each of the variations depicted in FIGS. 7.1-7.2 enable heat spreader 40to accommodate the varying dimensions of the multiple components andensure alignment of heat spreader 40 with stiffener 34 and dies 30 inthe package.

FIGS. 8.1-8.4 illustrate different configurations of one or more dies 30and the use of an interposer 54. First, FIG. 8.1 depicts a semiconductordevice package assembly 56 using one (1) die 30 attached to substrate32. Die 30 has thermal interface material 44 attached to its top surfaceto assist with thermal connectivity between die 30 and heat spreader 40.While FIG. 8.1 illustrates using one (1) die 30, it is contemplated thatmore than one (1) die 30 may be used.

Next, FIG. 8.2 shows a semiconductor device package assembly 58including interposer 54 disposed between die 30 and substrate 32.Interposer 54 is able to provide power connectivity and signalconnectivity between die 30 and substrate 32. One having ordinary skillin the art will recognize that interposer 54 can be made of materialssuch as silicon, glass, and other materials than can host electricalcircuits. Further, it is contemplated that interposer 54 can be apassive circuit or an active integrated circuit, such as a memorydevice, a radio frequency (RF) analog device, and amicro-electro-mechanical systems (MEMS) device. Thermal interfacematerial 44 is applied to the top surface of die 30 in order to assistwith thermal connectivity between die 30 and heat spreader 40.

FIG. 8.3 illustrates a semiconductor device package assembly 60including interposer 54 disposed between two (2) dies 30 and substrate32. As previously mentioned, interposer 54 can provide powerconnectivity and signal connectivity between dies 30 and substrate 32.Interposer 54 is made of a material such as silicon, glass, or othermaterials able to host electrical circuits. As discussed above,interposer 54 can be a passive circuit or an active integrated circuit,such as a memory device, an RF device, and a MEMS device. Theapplication of thermal interface material 44 to the top surface of eachdie 30 assists with the thermal connectivity between each die 30 andheat spreader 40. While FIG. 8.3 shows the use of two (2) dies 30, it iscontemplated that more or less dies 30 may be used. Further, it iscontemplated that additional dies 30 may be connected directly tosubstrate 32, and not through interposer 54.

Next, FIG. 8.4 depicts a semiconductor device package assembly 62according to an embodiment of the invention using an alternative stackarrangement. In this embodiment, at least one die 30 is attached tosubstrate 32. While FIG. 8.4 shows two (2) dies 30 attached to substrate32, it is contemplated that more or less than two (2) dies 30 may beattached to substrate 32. Interposer 54 is then attached to the topsurfaces of dies 30. Package assembly 62 further includes at least oneadditional die 30 attached to the top surface of interposer 54. Eventhough FIG. 8.4 illustrates one (1) die 30 attached to the top surfaceof interposer 54, it is contemplated that more dies 30 may be attachedto the top surface of interposer 54. Thermal interface material 44 isalso applied to the dies 30 attached to the top surface of interposer 54to achieve thermal connectivity between dies 30 and heat spreader 40. Inthis embodiment, interposer 54 can provide power connectivity and signalconnectivity between dies 30 located on both sides of interposer 54 andsubstrate 32. As previously mentioned, interposer 54 is made of amaterial such as silicon, glass, or other materials able to hostelectrical circuits. Further, interposer 54 can be a passive circuit oran active integrated circuit, such as a memory device, an RF device, anda MEMS device.

With respect to FIGS. 8.1-8.4, each semiconductor device packageassembly 56, 58, 60 also includes attaching stiffener 34 to substrate 32via adhesive 36. Stiffener 34 also includes at least one support stud 38attached thereto. While FIGS. 8.1-8.4 all depict two (2) support studs38, it is contemplated that less or more support studs 38 may be used.Each semiconductor device package assembly 56, 58, 60, 62 furtherincludes heat spreader 40, and heat spreader 40 includes at least onesupport path 42. Once again, while FIGS. 8.1-8.4 only depict two (2)support paths 42, it is contemplated that one or more support paths 42may be used. Specifically, the number of support paths 42 coincides withthe number of support studs 38. In addition, each support path 42 isaligned with a respective support stud 38. Thermal interface material 44is also applied to the top portion of each die 30 to achieve thermalconnectivity between dies 30 and heat spreader 40, when heat spreader 40is positioned in its final location.

The interaction between support studs 38 and support paths 42 allows forheat spreader 40 to be adjusted in the direction of support studs 38.The adjustable positioning of heat spreader 40 and the deforming ofthermal interface material 44 allows for thermal contact between heatspreader 40 and each die 30, which allows the yield of the package to besustained even in multi-die arrangements with components having varyingthicknesses.

Now referring to FIG. 9, an enlarged view of support stud 38 andstiffener 34 is provided, according to an embodiment of the invention.In this embodiment, support stud 38 includes a plated layer 64. Platedlayer 64 is created from either a two phase material or liquid metalmaterial. Further, plated layer 64 allows for bonding between supportstud 38 and its respective support path 42. Bonding is accomplished byplacing support stud 38 within support path 42 and subjecting thecombination to a heating process. Once heat spreader 40 (not shown) isin proper thermal contact with each die 30, bonding secures heatspreader 40 so that thermal contact with each die 30 is maintained.

In an alternative embodiment of the invention, support paths 42 may beformed in stiffener 34, as opposed to heat spreader 40. As a result,support studs 38 would be coupled to heat spreader 40, as opposed tostiffener 34. In this embodiment, the interaction between support studs38 and support paths 42 allows heat spreader 40 to be adjusted in thedirection of support studs 38. The variable positioning of heat spreader40 and the deforming of thermal interface material 44 allows for thermalcontact between heat spreader 40 and each die 30 resulting in sustainedyield of the package with the addition of multi-die arrangements.

In summary, using a heat spreader able to adjust its position beforebeing secured in place provides for a semiconductor device assemblypackage which can be adjusted for a range of thicknesses and tolerancesof different devices and components used within the assembly package.This results in a better thermal connection between the heat spreaderand the devices of the package, which in turn allows for a package tocontain multiple dies without sacrificing the yield of the package.

Therefore, according to one embodiment of the invention, a semiconductordevice packaging system includes a substrate, a heat spreader, astiffener attached to the substrate, and at least one die electricallycoupled to the substrate and thermally coupled to the heat spreader. Thesemiconductor device packaging system further includes at least one studcoupled to one of the stiffener and the heat spreader and at least oneorifice formed through one of the stiffener and the heat spreader. Inaddition, the at least one orifice is aligned with the at least onestud.

According to another aspect of the invention, a method of assembling asemiconductor device package includes electrically coupling at least onedie with a substrate, coupling a stiffener to the substrate, andcoupling at least one stud to one of the stiffener and a heat spreader.The method further includes forming at least one orifice through one ofthe stiffener and the heat spreader, aligning the at least one stud withthe at least one orifice to align the heat spreader, the stiffener, andthe at least one die, and thermally coupling the heat spreader with theat least one die.

According to yet another aspect of the invention, a flexible toleranceheat spreader for use with a semiconductor device package includes atleast one support path formed through the flexible tolerance heatspreader, wherein the at least one support path interacts with at leastone stud coupled to a stiffener of the semiconductor device package. Inaddition, the flexible tolerance heat spreader is variably positionedalong a direction of the interaction of the at least one support pathand the at least one stud to establish guidance of the flexibletolerance heat spreader to provide thermal contact with at least one dieof the substrate.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A semiconductor device packaging systemcomprising: a substrate; a heat spreader; a ring-shaped stiffenerattached to the substrate; at least one die electrically coupled to thesubstrate and thermally coupled to the heat spreader; at least one studcoupled to one of the ring-shaped stiffener and the heat spreader; andat least one orifice formed through one of the ring-shaped stiffener andthe heat spreader, the at least one orifice aligned with the at leastone stud; wherein the ring-shaped stiffener and the heat spreader are indirect contact with each other or have an air gap disposed therebetween.2. The system of claim 1 further comprising an interposer electricallycoupled to the substrate, wherein the interposer is displaced betweenthe substrate and the at least one die.
 3. The system of claim 2 whereinthe interposer provides power connectivity and signal connectivitybetween the substrate and the at least one die.
 4. The system of claim 2wherein the interposer is one of a passive circuit device and an activecircuit device.
 5. The system of claim 1 wherein the at least one studand the at least one orifice enables alignment of the heat spreader, thering-shaped stiffener, and the least one die; and a thermal interfacematerial is disposed between the at least one die and the heat spreader.6. The system of claim 5 wherein the thermal interface material iscompressed between the at least one die and the heat spreader.
 7. Thesystem of claim 1 wherein the at least one stud includes a plated layer,wherein the plated layer establishes a bond between the at least onestud and the heat spreader when subjected to a heating process.
 8. Thesystem of claim 7 wherein the plated layer can be one of a two-phasematerial and a liquid metal material.
 9. The system of claim 1 whereinthe at least one die is at least one of a high power device and a lowpower device.
 10. The system of claim 1 wherein the at least one diecomprises a plurality of dies, wherein at least one of the plurality ofdies is a high power device and at least another of the plurality ofdies is a low power device.
 11. A method of assembling a semiconductordevice package comprising: electrically coupling at least one die with asubstrate; coupling a ring-shaped stiffener to the substrate; couplingat least one stud to one of the ring-shaped stiffener and a heatspreader; forming at least one orifice through one of the ring-shapedstiffener and the heat spreader; aligning the at least one stud with theat least one orifice to align the heat spreader, the ring-shapedstiffener, and the at least one die; and thermally coupling the heatspreader with the at least one die; wherein, in aligning the heatspreader, the ring-shaped stiffener, and the at least one die, thering-shaped stiffener and the heat spreader are positioned so as to bein direct contact with each other or have an air gap disposedtherebetween.
 12. The method of claim 11 further comprising inserting aninterposer between the at least one die and the substrate.
 13. Themethod of claim 11 further comprising disposing a thermal interfacematerial between the at least one die and the heat spreader.
 14. Themethod of claim 11 further comprising applying a plated layer to the atleast one stud.
 15. The method of claim 14 further comprising heatingthe at least one stud, the plated layer, and the orifice to establish abond between the at least one stud and the at least one orifice.
 16. Aflexible tolerance heat spreader for use with a semiconductor devicepackage, the flexible tolerance heat spreader comprising: at least onesupport path formed therethrough; wherein the at least one support pathinteracts with at least one stud coupled to a metal ring of thesemiconductor device package; wherein the flexible tolerance heatspreader is variably positioned along a direction of the interaction ofthe at least one support path and the at least one stud to establishguidance of the fleixble tolerance heat spreader to provide thermalcontact with at least one die of the substrate; and wherein the flexibletolerance heat spreader is in direct contact with the metal ring of thesemiconductor device package or separated from the metal ring of thesemiconductor device package by an air gap disposed therebetween. 17.The flexible tolerance heat spreader of claim 16 wherein a thermalinterface material initiates thermal contact between the flexibletolerance heat spreader and the at least one die of the substrate. 18.The flexible tolerance heat spreader of claim 17 wherein the thermalinterface material is deformed when the flexible tolerance heat spreaderand the at least one die of the substrate are placed in thermal contact.19. The flexible tolerance heat spreader of claim 16 wherein the atleast one stud has a plated layer.
 20. The flexible tolerance heatspreader of claim 19 wherein the plated layer of the at least one studestablishes a bond between the at least one stud and the flexibletolerance heat spreader when heated.
 21. The flexible tolerance heatspreader of claim 20 wherein the plated layer can be one of a two-phasematerial and a liquid metal material.